/*
 *  Overview:
 *   Bad block table support for the NAND driver
 *
 *  Copyright © 2004 Thomas Gleixner (tglx@linutronix.de)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Description:
 *
 * When nand_scan_bbt is called, then it tries to find the bad block table
 * depending on the options in the BBT descriptor(s). If no flash based BBT
 * (NAND_BBT_USE_FLASH) is specified then the device is scanned for factory
 * marked good / bad blocks. This information is used to create a memory BBT.
 * Once a new bad block is discovered then the "factory" information is updated
 * on the device.
 * If a flash based BBT is specified then the function first tries to find the
 * BBT on flash. If a BBT is found then the contents are read and the memory
 * based BBT is created. If a mirrored BBT is selected then the mirror is
 * searched too and the versions are compared. If the mirror has a greater
 * version number, then the mirror BBT is used to build the memory based BBT.
 * If the tables are not versioned, then we "or" the bad block information.
 * If one of the BBTs is out of date or does not exist it is (re)created.
 * If no BBT exists at all then the device is scanned for factory marked
 * good / bad blocks and the bad block tables are created.
 *
 * For manufacturer created BBTs like the one found on M-SYS DOC devices
 * the BBT is searched and read but never created
 *
 * The auto generated bad block table is located in the last good blocks
 * of the device. The table is mirrored, so it can be updated eventually.
 * The table is marked in the OOB area with an ident pattern and a version
 * number which indicates which of both tables is more up to date. If the NAND
 * controller needs the complete OOB area for the ECC information then the
 * option NAND_BBT_NO_OOB should be used (along with NAND_BBT_USE_FLASH, of
 * course): it moves the ident pattern and the version byte into the data area
 * and the OOB area will remain untouched.
 *
 * The table uses 2 bits per block
 * 11b:     block is good
 * 00b:     block is factory marked bad
 * 01b, 10b:    block is marked bad due to wear
 *
 * The memory bad block table uses the following scheme:
 * 00b:     block is good
 * 01b:     block is marked bad due to wear
 * 10b:     block is reserved (to protect the bbt area)
 * 11b:     block is factory marked bad
 *
 * Multichip devices like DOC store the bad block info per floor.
 *
 * Following assumptions are made:
 * - bbts start at a page boundary, if autolocated on a block boundary
 * - the space necessary for a bbt in FLASH does not exceed a block boundary
 *
 */

//#include <common.h>
#include <rtthread.h>
//#include <malloc.h>
#include <linux/compat.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/bbm.h>
#include <linux/mtd/nand.h>
//#include <linux/bitops.h>
//#include <linux/string.h>
//#include "yaffs_malloc.h"

#define BBT_BLOCK_GOOD      0x00
#define BBT_BLOCK_WORN      0x01
#define BBT_BLOCK_RESERVED  0x02
#define BBT_BLOCK_FACTORY_BAD   0x03

#define BBT_ENTRY_MASK      0x03
#define BBT_ENTRY_SHIFT     2

static int nand_update_bbt(struct mtd_info *mtd, loff_t offs);

static __inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
{
    uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
    entry >>= (block & BBT_ENTRY_MASK) * 2;
    return entry & BBT_ENTRY_MASK;
}

static __inline void bbt_mark_entry(struct nand_chip *chip, int block,
                                    uint8_t mark)
{
    uint8_t msk = (mark & BBT_ENTRY_MASK) << ((block & BBT_ENTRY_MASK) * 2);
    chip->bbt[block >> BBT_ENTRY_SHIFT] |= msk;
}

static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
{
    if (rt_memcmp(buf, td->pattern, td->len))
        return -1;
    return 0;
}

/**
 * check_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf: the buffer to search
 * @len: the length of buffer to search
 * @paglen: the pagelength
 * @td: search pattern descriptor
 *
 * Check for a pattern at the given place. Used to search bad block tables and
 * good / bad block identifiers.
 */
static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
{
    if (td->options & NAND_BBT_NO_OOB)
        return check_pattern_no_oob(buf, td);

    /* Compare the pattern */
    if (rt_memcmp(buf + paglen + td->offs, td->pattern, td->len))
        return -1;

    return 0;
}

/**
 * check_short_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf: the buffer to search
 * @td: search pattern descriptor
 *
 * Check for a pattern at the given place. Used to search bad block tables and
 * good / bad block identifiers. Same as check_pattern, but no optional empty
 * check.
 */
static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
{
    /* Compare the pattern */
    if (rt_memcmp(buf + td->offs, td->pattern, td->len))
        return -1;
    return 0;
}

/**
 * add_marker_len - compute the length of the marker in data area
 * @td: BBT descriptor used for computation
 *
 * The length will be 0 if the marker is located in OOB area.
 */
static u32 add_marker_len(struct nand_bbt_descr *td)
{
    u32 len;

    if (!(td->options & NAND_BBT_NO_OOB))
        return 0;

    len = td->len;
    if (td->options & NAND_BBT_VERSION)
        len++;
    return len;
}

/**
 * read_bbt - [GENERIC] Read the bad block table starting from page
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @page: the starting page
 * @num: the number of bbt descriptors to read
 * @td: the bbt describtion table
 * @offs: block number offset in the table
 *
 * Read the bad block table starting from page.
 */
static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                    struct nand_bbt_descr *td, int offs)
{
    int res, ret = 0, i, j, act = 0;
    struct nand_chip *this = mtd_to_nand(mtd);
    size_t retlen, len, totlen;
    loff_t from;
    int bits = td->options & NAND_BBT_NRBITS_MSK;
    uint8_t msk = (uint8_t)((1 << bits) - 1);
    u32 marker_len;
    int reserved_block_code = td->reserved_block_code;

    totlen = (num * bits) >> 3;
    marker_len = add_marker_len(td);
    from = ((loff_t)page) << this->page_shift;

    while (totlen)
    {
        len = min(totlen, (size_t)(1 << this->bbt_erase_shift));
        if (marker_len)
        {
            /*
             * In case the BBT marker is not in the OOB area it
             * will be just in the first page.
             */
            len -= marker_len;
            from += marker_len;
            marker_len = 0;
        }
        res = mtd_read(mtd, from, len, &retlen, buf);
        if (res < 0)
        {
            if (mtd_is_eccerr(res))
            {
                pr_info("nand_bbt: ECC error in BBT at 0x%012llx\n",
                        from & ~mtd->writesize);
                return res;
            }
            else if (mtd_is_bitflip(res))
            {
                pr_info("nand_bbt: corrected error in BBT at 0x%012llx\n",
                        from & ~mtd->writesize);
                ret = res;
            }
            else
            {
                pr_info("nand_bbt: error reading BBT\n");
                return res;
            }
        }

        /* Analyse data */
        for (i = 0; i < len; i++)
        {
            uint8_t dat = buf[i];
            for (j = 0; j < 8; j += bits, act++)
            {
                uint8_t tmp = (dat >> j) & msk;
                if (tmp == msk)
                    continue;
                if (reserved_block_code && (tmp == reserved_block_code))
                {
                    pr_info("nand_read_bbt: reserved block at 0x%012llx\n",
                            (loff_t)(offs + act) <<
                            this->bbt_erase_shift);
                    bbt_mark_entry(this, offs + act,
                                   BBT_BLOCK_RESERVED);
                    mtd->ecc_stats.bbtblocks++;
                    continue;
                }
                /*
                 * Leave it for now, if it's matured we can
                 * move this message to pr_debug.
                 */
                pr_info("nand_read_bbt: bad block at 0x%012llx\n",
                        (loff_t)(offs + act) <<
                        this->bbt_erase_shift);
                /* Factory marked bad or worn out? */
                if (tmp == 0)
                    bbt_mark_entry(this, offs + act,
                                   BBT_BLOCK_FACTORY_BAD);
                else
                    bbt_mark_entry(this, offs + act,
                                   BBT_BLOCK_WORN);
                mtd->ecc_stats.badblocks++;
            }
        }
        totlen -= len;
        from += len;
    }
    return ret;
}

/**
 * read_abs_bbt - [GENERIC] Read the bad block table starting at a given page
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 * @chip: read the table for a specific chip, -1 read all chips; applies only if
 *        NAND_BBT_PERCHIP option is set
 *
 * Read the bad block table for all chips starting at a given page. We assume
 * that the bbt bits are in consecutive order.
 */
static int read_abs_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td, int chip)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int res = 0, i;

    if (td->options & NAND_BBT_PERCHIP)
    {
        int offs = 0;
        for (i = 0; i < this->numchips; i++)
        {
            if (chip == -1 || chip == i)
                res = read_bbt(mtd, buf, td->pages[i],
                               this->chipsize >> this->bbt_erase_shift,
                               td, offs);
            if (res)
                return res;
            offs += this->chipsize >> this->bbt_erase_shift;
        }
    }
    else
    {
        res = read_bbt(mtd, buf, td->pages[0],
                       mtd->size >> this->bbt_erase_shift, td, 0);
        if (res)
            return res;
    }
    return 0;
}

/* BBT marker is in the first page, no OOB */
static int scan_read_data(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
                          struct nand_bbt_descr *td)
{
    size_t retlen;
    size_t len;

    len = td->len;
    if (td->options & NAND_BBT_VERSION)
        len++;

    return mtd_read(mtd, offs, len, &retlen, buf);
}

/**
 * scan_read_oob - [GENERIC] Scan data+OOB region to buffer
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @offs: offset at which to scan
 * @len: length of data region to read
 *
 * Scan read data from data+OOB. May traverse multiple pages, interleaving
 * page,OOB,page,OOB,... in buf. Completes transfer and returns the "strongest"
 * ECC condition (error or bitflip). May quit on the first (non-ECC) error.
 */
static int scan_read_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
                         size_t len)
{
    struct mtd_oob_ops ops;
    int res, ret = 0;

    ops.mode = MTD_OPS_PLACE_OOB;
    ops.ooboffs = 0;
    ops.ooblen = mtd->oobsize;

    while (len > 0)
    {
        ops.datbuf = buf;
        ops.len = min(len, (size_t)mtd->writesize);
        ops.oobbuf = buf + ops.len;

        res = mtd_read_oob(mtd, offs, &ops);
        if (res)
        {
            if (!mtd_is_bitflip_or_eccerr(res))
                return res;
            else if (mtd_is_eccerr(res) || !ret)
                ret = res;
        }

        buf += mtd->oobsize + mtd->writesize;
        len -= mtd->writesize;
        offs += mtd->writesize;
    }
    return ret;
}

static int scan_read(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
                     size_t len, struct nand_bbt_descr *td)
{
    if (td->options & NAND_BBT_NO_OOB)
        return scan_read_data(mtd, buf, offs, td);
    else
        return scan_read_oob(mtd, buf, offs, len);
}

/* Scan write data with oob to flash */
static int scan_write_bbt(struct mtd_info *mtd, loff_t offs, size_t len,
                          uint8_t *buf, uint8_t *oob)
{
    struct mtd_oob_ops ops;

    ops.mode = MTD_OPS_PLACE_OOB;
    ops.ooboffs = 0;
    ops.ooblen = mtd->oobsize;
    ops.datbuf = buf;
    ops.oobbuf = oob;
    ops.len = len;

    return mtd_write_oob(mtd, offs, &ops);
}

static u32 bbt_get_ver_offs(struct mtd_info *mtd, struct nand_bbt_descr *td)
{
    u32 ver_offs = td->veroffs;

    if (!(td->options & NAND_BBT_NO_OOB))
        ver_offs += mtd->writesize;
    return ver_offs;
}

/**
 * read_abs_bbts - [GENERIC] Read the bad block table(s) for all chips starting at a given page
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 * @md: descriptor for the bad block table mirror
 *
 * Read the bad block table(s) for all chips starting at a given page. We
 * assume that the bbt bits are in consecutive order.
 */
static void read_abs_bbts(struct mtd_info *mtd, uint8_t *buf,
                          struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
    struct nand_chip *this = mtd_to_nand(mtd);

    /* Read the primary version, if available */
    if (td->options & NAND_BBT_VERSION)
    {
        scan_read(mtd, buf, (loff_t)td->pages[0] << this->page_shift,
                  mtd->writesize, td);
        td->version[0] = buf[bbt_get_ver_offs(mtd, td)];
        pr_info("Bad block table at page %d, version 0x%02X\n",
                td->pages[0], td->version[0]);
    }

    /* Read the mirror version, if available */
    if (md && (md->options & NAND_BBT_VERSION))
    {
        scan_read(mtd, buf, (loff_t)md->pages[0] << this->page_shift,
                  mtd->writesize, md);
        md->version[0] = buf[bbt_get_ver_offs(mtd, md)];
        pr_info("Bad block table at page %d, version 0x%02X\n",
                md->pages[0], md->version[0]);
    }
}

/* Scan a given block partially */
static int scan_block_fast(struct mtd_info *mtd, struct nand_bbt_descr *bd,
                           loff_t offs, uint8_t *buf, int numpages)
{
    struct mtd_oob_ops ops;
    int j, ret;

    ops.ooblen = mtd->oobsize;
    ops.oobbuf = buf;
    ops.ooboffs = 0;
    ops.datbuf = NULL;
    ops.mode = MTD_OPS_PLACE_OOB;

    for (j = 0; j < numpages; j++)
    {
        /*
         * Read the full oob until read_oob is fixed to handle single
         * byte reads for 16 bit buswidth.
         */
        ret = mtd_read_oob(mtd, offs, &ops);
        /* Ignore ECC errors when checking for BBM */
        if (ret && !mtd_is_bitflip_or_eccerr(ret))
            return ret;

        if (check_short_pattern(buf, bd))
            return 1;

        offs += mtd->writesize;
    }
    return 0;
}

/**
 * create_bbt - [GENERIC] Create a bad block table by scanning the device
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @bd: descriptor for the good/bad block search pattern
 * @chip: create the table for a specific chip, -1 read all chips; applies only
 *        if NAND_BBT_PERCHIP option is set
 *
 * Create a bad block table by scanning the device for the given good/bad block
 * identify pattern.
 */
static int create_bbt(struct mtd_info *mtd, uint8_t *buf,
                      struct nand_bbt_descr *bd, int chip)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int i, numblocks, numpages;
    int startblock;
    loff_t from;

    rt_kprintf("Scanning device for bad blocks\n");

    if (bd->options & NAND_BBT_SCAN2NDPAGE)
        numpages = 2;
    else
        numpages = 1;

    if (chip == -1)
    {
        numblocks = mtd->size >> this->bbt_erase_shift;
        startblock = 0;
        from = 0;
    }
    else
    {
        if (chip >= this->numchips)
        {
            pr_warn("create_bbt(): chipnr (%d) > available chips (%d)\n",
                    chip + 1, this->numchips);
            return -EINVAL;
        }
        numblocks = this->chipsize >> this->bbt_erase_shift;
        startblock = chip * numblocks;
        numblocks += startblock;
        from = (loff_t)startblock << this->bbt_erase_shift;
    }

    if (this->bbt_options & NAND_BBT_SCANLASTPAGE)
        from += mtd->erasesize - (mtd->writesize * numpages);

    for (i = startblock; i < numblocks; i++)
    {
        int ret;

        BUG_ON(bd->options & NAND_BBT_NO_OOB);

        ret = scan_block_fast(mtd, bd, from, buf, numpages);
        if (ret < 0)
            return ret;

        if (ret)
        {
            bbt_mark_entry(this, i, BBT_BLOCK_FACTORY_BAD);
            rt_kprintf("Bad eraseblock %d at 0x%08x\n", i, (unsigned int)from);
            mtd->ecc_stats.badblocks++;
        }

        from += (1 << this->bbt_erase_shift);
    }
    return 0;
}

/**
 * search_bbt - [GENERIC] scan the device for a specific bad block table
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 *
 * Read the bad block table by searching for a given ident pattern. Search is
 * preformed either from the beginning up or from the end of the device
 * downwards. The search starts always at the start of a block. If the option
 * NAND_BBT_PERCHIP is given, each chip is searched for a bbt, which contains
 * the bad block information of this chip. This is necessary to provide support
 * for certain DOC devices.
 *
 * The bbt ident pattern resides in the oob area of the first page in a block.
 */
static int search_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int i, chips;
    int startblock, block, dir;
    int scanlen = mtd->writesize + mtd->oobsize;
    int bbtblocks;
    int blocktopage = this->bbt_erase_shift - this->page_shift;

    /* Search direction top -> down? */
    if (td->options & NAND_BBT_LASTBLOCK)
    {
        startblock = (mtd->size >> this->bbt_erase_shift) - 1;
        dir = -1;
    }
    else
    {
        startblock = 0;
        dir = 1;
    }

    /* Do we have a bbt per chip? */
    if (td->options & NAND_BBT_PERCHIP)
    {
        chips = this->numchips;
        bbtblocks = this->chipsize >> this->bbt_erase_shift;
        startblock &= bbtblocks - 1;
    }
    else
    {
        chips = 1;
        bbtblocks = mtd->size >> this->bbt_erase_shift;
    }

    for (i = 0; i < chips; i++)
    {
        /* Reset version information */
        td->version[i] = 0;
        td->pages[i] = -1;
        /* Scan the maximum number of blocks */
        for (block = 0; block < td->maxblocks; block++)
        {

            int actblock = startblock + dir * block;
            loff_t offs = (loff_t)actblock << this->bbt_erase_shift;

            /* Read first page */
            scan_read(mtd, buf, offs, mtd->writesize, td);
            if (!check_pattern(buf, scanlen, mtd->writesize, td))
            {
                td->pages[i] = actblock << blocktopage;
                if (td->options & NAND_BBT_VERSION)
                {
                    offs = bbt_get_ver_offs(mtd, td);
                    td->version[i] = buf[offs];
                }
                break;
            }
        }
        startblock += this->chipsize >> this->bbt_erase_shift;
    }
    /* Check, if we found a bbt for each requested chip */
    for (i = 0; i < chips; i++)
    {
        if (td->pages[i] == -1)
            pr_warn("Bad block table not found for chip %d\n", i);
        else
            pr_info("Bad block table found at page %d, version 0x%02X\n",
                    td->pages[i], td->version[i]);
    }
    return 0;
}

/**
 * search_read_bbts - [GENERIC] scan the device for bad block table(s)
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 * @md: descriptor for the bad block table mirror
 *
 * Search and read the bad block table(s).
 */
static void search_read_bbts(struct mtd_info *mtd, uint8_t *buf,
                             struct nand_bbt_descr *td,
                             struct nand_bbt_descr *md)
{
    /* Search the primary table */
    search_bbt(mtd, buf, td);

    /* Search the mirror table */
    if (md)
        search_bbt(mtd, buf, md);
}

/**
 * write_bbt - [GENERIC] (Re)write the bad block table
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 * @md: descriptor for the bad block table mirror
 * @chipsel: selector for a specific chip, -1 for all
 *
 * (Re)write the bad block table.
 */
static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
                     struct nand_bbt_descr *td, struct nand_bbt_descr *md,
                     int chipsel)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    struct erase_info einfo;
    int i, res, chip = 0;
    int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
    int nrchips, pageoffs, ooboffs;
    uint8_t msk[4];
    uint8_t rcode = td->reserved_block_code;
    size_t retlen, len = 0;
    loff_t to;
    struct mtd_oob_ops ops;

    ops.ooblen = mtd->oobsize;
    ops.ooboffs = 0;
    ops.datbuf = NULL;
    ops.mode = MTD_OPS_PLACE_OOB;

    if (!rcode)
        rcode = 0xff;
    /* Write bad block table per chip rather than per device? */
    if (td->options & NAND_BBT_PERCHIP)
    {
        numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
        /* Full device write or specific chip? */
        if (chipsel == -1)
        {
            nrchips = this->numchips;
        }
        else
        {
            nrchips = chipsel + 1;
            chip = chipsel;
        }
    }
    else
    {
        numblocks = (int)(mtd->size >> this->bbt_erase_shift);
        nrchips = 1;
    }

    /* Loop through the chips */
    for (; chip < nrchips; chip++)
    {
        /*
         * There was already a version of the table, reuse the page
         * This applies for absolute placement too, as we have the
         * page nr. in td->pages.
         */
        if (td->pages[chip] != -1)
        {
            page = td->pages[chip];
            goto write;
        }

        /*
         * Automatic placement of the bad block table. Search direction
         * top -> down?
         */
        if (td->options & NAND_BBT_LASTBLOCK)
        {
            startblock = numblocks * (chip + 1) - 1;
            dir = -1;
        }
        else
        {
            startblock = chip * numblocks;
            dir = 1;
        }

        for (i = 0; i < td->maxblocks; i++)
        {
            int block = startblock + dir * i;
            /* Check, if the block is bad */
            switch (bbt_get_entry(this, block))
            {
            case BBT_BLOCK_WORN:
            case BBT_BLOCK_FACTORY_BAD:
                continue;
            }
            page = block <<
                   (this->bbt_erase_shift - this->page_shift);
            /* Check, if the block is used by the mirror table */
            if (!md || md->pages[chip] != page)
                goto write;
        }
        pr_err("No space left to write bad block table\n");
        return -ENOSPC;
write:

        /* Set up shift count and masks for the flash table */
        bits = td->options & NAND_BBT_NRBITS_MSK;
        msk[2] = ~rcode;
        switch (bits)
        {
        case 1:
            sft = 3;
            sftmsk = 0x07;
            msk[0] = 0x00;
            msk[1] = 0x01;
            msk[3] = 0x01;
            break;
        case 2:
            sft = 2;
            sftmsk = 0x06;
            msk[0] = 0x00;
            msk[1] = 0x01;
            msk[3] = 0x03;
            break;
        case 4:
            sft = 1;
            sftmsk = 0x04;
            msk[0] = 0x00;
            msk[1] = 0x0C;
            msk[3] = 0x0f;
            break;
        case 8:
            sft = 0;
            sftmsk = 0x00;
            msk[0] = 0x00;
            msk[1] = 0x0F;
            msk[3] = 0xff;
            break;
        default:
            return -EINVAL;
        }

        to = ((loff_t)page) << this->page_shift;

        /* Must we save the block contents? */
        if (td->options & NAND_BBT_SAVECONTENT)
        {
            /* Make it block aligned */
            to &= ~(((loff_t)1 << this->bbt_erase_shift) - 1);
            len = 1 << this->bbt_erase_shift;
            res = mtd_read(mtd, to, len, &retlen, buf);
            if (res < 0)
            {
                if (retlen != len)
                {
                    pr_info("nand_bbt: error reading block for writing the bad block table\n");
                    return res;
                }
                pr_warn("nand_bbt: ECC error while reading block for writing bad block table\n");
            }
            /* Read oob data */
            ops.ooblen = (len >> this->page_shift) * mtd->oobsize;
            ops.oobbuf = &buf[len];
            res = mtd_read_oob(mtd, to + mtd->writesize, &ops);
            if (res < 0 || ops.oobretlen != ops.ooblen)
                goto outerr;

            /* Calc the byte offset in the buffer */
            pageoffs = page - (int)(to >> this->page_shift);
            offs = pageoffs << this->page_shift;
            /* Preset the bbt area with 0xff */
            memset(&buf[offs], 0xff, (size_t)(numblocks >> sft));
            ooboffs = len + (pageoffs * mtd->oobsize);

        }
        else if (td->options & NAND_BBT_NO_OOB)
        {
            ooboffs = 0;
            offs = td->len;
            /* The version byte */
            if (td->options & NAND_BBT_VERSION)
                offs++;
            /* Calc length */
            len = (size_t)(numblocks >> sft);
            len += offs;
            /* Make it page aligned! */
            //len = ALIGN(len, mtd->writesize);
            if (len < mtd->writesize)
                len = mtd->writesize;
            else
                len = 0;
            /* Preset the buffer with 0xff */
            memset(buf, 0xff, len);
            /* Pattern is located at the begin of first page */
            memcpy(buf, td->pattern, td->len);
        }
        else
        {
            /* Calc length */
            len = (size_t)(numblocks >> sft);
            /* Make it page aligned! */
            //len = ALIGN(len, mtd->writesize);
            if (len < mtd->writesize)
                len = mtd->writesize;
            else
                len = 0;
            /* Preset the buffer with 0xff */
            memset(buf, 0xff, len +
                   (len >> this->page_shift)* mtd->oobsize);
            offs = 0;
            ooboffs = len;
            /* Pattern is located in oob area of first page */
            memcpy(&buf[ooboffs + td->offs], td->pattern, td->len);
        }

        if (td->options & NAND_BBT_VERSION)
            buf[ooboffs + td->veroffs] = td->version[chip];

        /* Walk through the memory table */
        for (i = 0; i < numblocks; i++)
        {
            uint8_t dat;
            int sftcnt = (i << (3 - sft)) & sftmsk;
            dat = bbt_get_entry(this, chip * numblocks + i);
            /* Do not store the reserved bbt blocks! */
            buf[offs + (i >> sft)] &= ~(msk[dat] << sftcnt);
        }

        memset(&einfo, 0, sizeof(einfo));
        einfo.mtd = mtd;
        einfo.addr = to;
        einfo.len = 1 << this->bbt_erase_shift;
        res = nand_erase_nand(mtd, &einfo, 1);
        if (res < 0)
            goto outerr;

        res = scan_write_bbt(mtd, to, len, buf,
                             td->options & NAND_BBT_NO_OOB ? NULL :
                             &buf[len]);
        if (res < 0)
            goto outerr;

        pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
                (unsigned long long)to, td->version[chip]);

        /* Mark it as used */
        td->pages[chip] = page;
    }
    return 0;

outerr:
    pr_warn("nand_bbt: error while writing bad block table %d\n", res);
    return res;
}

/**
 * nand_memory_bbt - [GENERIC] create a memory based bad block table
 * @mtd: MTD device structure
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function creates a memory based bbt by scanning the device for
 * manufacturer / software marked good / bad blocks.
 */
static __inline int nand_memory_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
    struct nand_chip *this = mtd_to_nand(mtd);

    return create_bbt(mtd, this->buffers->databuf, bd, -1);
}

/**
 * check_create - [GENERIC] create and write bbt(s) if necessary
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function checks the results of the previous call to read_bbt and creates
 * / updates the bbt(s) if necessary. Creation is necessary if no bbt was found
 * for the chip/device. Update is necessary if one of the tables is missing or
 * the version nr. of one table is less than the other.
 */
static int check_create(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd)
{
    int i, chips, writeops, create, chipsel, res, res2;
    struct nand_chip *this = mtd_to_nand(mtd);
    struct nand_bbt_descr *td = this->bbt_td;
    struct nand_bbt_descr *md = this->bbt_md;
    struct nand_bbt_descr *rd, *rd2;

    /* Do we have a bbt per chip? */
    if (td->options & NAND_BBT_PERCHIP)
        chips = this->numchips;
    else
        chips = 1;

    for (i = 0; i < chips; i++)
    {
        writeops = 0;
        create = 0;
        rd = NULL;
        rd2 = NULL;
        res = res2 = 0;
        /* Per chip or per device? */
        chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
        /* Mirrored table available? */
        if (md)
        {
            if (td->pages[i] == -1 && md->pages[i] == -1)
            {
                create = 1;
                writeops = 0x03;
            }
            else if (td->pages[i] == -1)
            {
                rd = md;
                writeops = 0x01;
            }
            else if (md->pages[i] == -1)
            {
                rd = td;
                writeops = 0x02;
            }
            else if (td->version[i] == md->version[i])
            {
                rd = td;
                if (!(td->options & NAND_BBT_VERSION))
                    rd2 = md;
            }
            else if (((int8_t)(td->version[i] - md->version[i])) > 0)
            {
                rd = td;
                writeops = 0x02;
            }
            else
            {
                rd = md;
                writeops = 0x01;
            }
        }
        else
        {
            if (td->pages[i] == -1)
            {
                create = 1;
                writeops = 0x01;
            }
            else
            {
                rd = td;
            }
        }

        if (create)
        {
            /* Create the bad block table by scanning the device? */
            if (!(td->options & NAND_BBT_CREATE))
                continue;

            /* Create the table in memory by scanning the chip(s) */
            if (!(this->bbt_options & NAND_BBT_CREATE_EMPTY))
                create_bbt(mtd, buf, bd, chipsel);

            td->version[i] = 1;
            if (md)
                md->version[i] = 1;
        }

        /* Read back first? */
        if (rd)
        {
            res = read_abs_bbt(mtd, buf, rd, chipsel);
            if (mtd_is_eccerr(res))
            {
                /* Mark table as invalid */
                rd->pages[i] = -1;
                rd->version[i] = 0;
                i--;
                continue;
            }
        }
        /* If they weren't versioned, read both */
        if (rd2)
        {
            res2 = read_abs_bbt(mtd, buf, rd2, chipsel);
            if (mtd_is_eccerr(res2))
            {
                /* Mark table as invalid */
                rd2->pages[i] = -1;
                rd2->version[i] = 0;
                i--;
                continue;
            }
        }

        /* Scrub the flash table(s)? */
        if (mtd_is_bitflip(res) || mtd_is_bitflip(res2))
        {
            writeops = 0x03;
        }

        /* Update version numbers before writing */
        if (md)
        {
            td->version[i] = max(td->version[i], md->version[i]);
            md->version[i] = td->version[i];
        }

        /* Write the bad block table to the device? */
        if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE))
        {
            res = write_bbt(mtd, buf, td, md, chipsel);
            if (res < 0)
                return res;
        }

        /* Write the mirror bad block table to the device? */
        if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE))
        {
            res = write_bbt(mtd, buf, md, td, chipsel);
            if (res < 0)
                return res;
        }
    }
    return 0;
}

/**
 * mark_bbt_regions - [GENERIC] mark the bad block table regions
 * @mtd: MTD device structure
 * @td: bad block table descriptor
 *
 * The bad block table regions are marked as "bad" to prevent accidental
 * erasures / writes. The regions are identified by the mark 0x02.
 */
static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int i, j, chips, block, nrblocks, update;
    uint8_t oldval;

    /* Do we have a bbt per chip? */
    if (td->options & NAND_BBT_PERCHIP)
    {
        chips = this->numchips;
        nrblocks = (int)(this->chipsize >> this->bbt_erase_shift);
    }
    else
    {
        chips = 1;
        nrblocks = (int)(mtd->size >> this->bbt_erase_shift);
    }

    for (i = 0; i < chips; i++)
    {
        if ((td->options & NAND_BBT_ABSPAGE) ||
                !(td->options & NAND_BBT_WRITE))
        {
            if (td->pages[i] == -1)
                continue;
            block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
            oldval = bbt_get_entry(this, block);
            bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
            if ((oldval != BBT_BLOCK_RESERVED) &&
                    td->reserved_block_code)
                nand_update_bbt(mtd, (loff_t)block <<
                                this->bbt_erase_shift);
            continue;
        }
        update = 0;
        if (td->options & NAND_BBT_LASTBLOCK)
            block = ((i + 1) * nrblocks) - td->maxblocks;
        else
            block = i * nrblocks;
        for (j = 0; j < td->maxblocks; j++)
        {
            oldval = bbt_get_entry(this, block);
            bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
            if (oldval != BBT_BLOCK_RESERVED)
                update = 1;
            block++;
        }
        /*
         * If we want reserved blocks to be recorded to flash, and some
         * new ones have been marked, then we need to update the stored
         * bbts.  This should only happen once.
         */
        if (update && td->reserved_block_code)
            nand_update_bbt(mtd, (loff_t)(block - 1) <<
                            this->bbt_erase_shift);
    }
}

/**
 * verify_bbt_descr - verify the bad block description
 * @mtd: MTD device structure
 * @bd: the table to verify
 *
 * This functions performs a few sanity checks on the bad block description
 * table.
 */
static void verify_bbt_descr(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    u32 pattern_len;
    u32 bits;
    u32 table_size;

    if (!bd)
        return;

    pattern_len = bd->len;
    bits = bd->options & NAND_BBT_NRBITS_MSK;

    BUG_ON((this->bbt_options & NAND_BBT_NO_OOB) &&
           !(this->bbt_options & NAND_BBT_USE_FLASH));
    BUG_ON(!bits);

    if (bd->options & NAND_BBT_VERSION)
        pattern_len++;

    if (bd->options & NAND_BBT_NO_OOB)
    {
        BUG_ON(!(this->bbt_options & NAND_BBT_USE_FLASH));
        BUG_ON(!(this->bbt_options & NAND_BBT_NO_OOB));
        BUG_ON(bd->offs);
        if (bd->options & NAND_BBT_VERSION)
            BUG_ON(bd->veroffs != bd->len);
        BUG_ON(bd->options & NAND_BBT_SAVECONTENT);
    }

    if (bd->options & NAND_BBT_PERCHIP)
        table_size = this->chipsize >> this->bbt_erase_shift;
    else
        table_size = mtd->size >> this->bbt_erase_shift;
    table_size >>= 3;
    table_size *= bits;
    if (bd->options & NAND_BBT_NO_OOB)
        table_size += pattern_len;
    BUG_ON(table_size > (1 << this->bbt_erase_shift));
}

/**
 * nand_scan_bbt - [NAND Interface] scan, find, read and maybe create bad block table(s)
 * @mtd: MTD device structure
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function checks, if a bad block table(s) is/are already available. If
 * not it scans the device for manufacturer marked good / bad blocks and writes
 * the bad block table(s) to the selected place.
 *
 * The bad block table memory is allocated here. It must be freed by calling
 * the nand_free_bbt function.
 */
static int nand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int len, res;
    uint8_t *buf;
    struct nand_bbt_descr *td = this->bbt_td;
    struct nand_bbt_descr *md = this->bbt_md;

    len = mtd->size >> (this->bbt_erase_shift + 2);
    /*
     * Allocate memory (2bit per block) and clear the memory bad block
     * table.
     */
    this->bbt = rt_malloc(len);
    if (!this->bbt)
        return -ENOMEM;
    rt_memset((void *)this->bbt, 0, len);

    /*
     * If no primary table decriptor is given, scan the device to build a
     * memory based bad block table.
     */
    if (!td)
    {
        if ((res = nand_memory_bbt(mtd, bd)) < 0)
        {
            pr_err("nand_bbt: can't scan flash and build the RAM-based BBT\n");
            goto err;
        }
        return 0;
    }
    verify_bbt_descr(mtd, td);
    verify_bbt_descr(mtd, md);

    /* Allocate a temporary buffer for one eraseblock incl. oob */
    len = (1 << this->bbt_erase_shift);
    len += (len >> this->page_shift) * mtd->oobsize;
    buf = rt_malloc(len);
    if (!buf)
    {
        res = -ENOMEM;
        goto err;
    }

    /* Is the bbt at a given page? */
    if (td->options & NAND_BBT_ABSPAGE)
    {
        read_abs_bbts(mtd, buf, td, md);
    }
    else
    {
        /* Search the bad block table using a pattern in oob */
        search_read_bbts(mtd, buf, td, md);
    }

    res = check_create(mtd, buf, bd);
    if (res)
        goto err;

    /* Prevent the bbt regions from erasing / writing */
    mark_bbt_region(mtd, td);
    if (md)
        mark_bbt_region(mtd, md);

    rt_free(buf);
    return 0;

err:
    rt_free(this->bbt);
    this->bbt = NULL;
    return res;
}

/**
 * nand_update_bbt - update bad block table(s)
 * @mtd: MTD device structure
 * @offs: the offset of the newly marked block
 *
 * The function updates the bad block table(s).
 */
static int nand_update_bbt(struct mtd_info *mtd, loff_t offs)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int len, res = 0;
    int chip, chipsel;
    uint8_t *buf;
    struct nand_bbt_descr *td = this->bbt_td;
    struct nand_bbt_descr *md = this->bbt_md;

    if (!this->bbt || !td)
        return -EINVAL;

    /* Allocate a temporary buffer for one eraseblock incl. oob */
    len = (1 << this->bbt_erase_shift);
    len += (len >> this->page_shift) * mtd->oobsize;
    buf = rt_malloc(len);
    if (!buf)
        return -ENOMEM;

    /* Do we have a bbt per chip? */
    if (td->options & NAND_BBT_PERCHIP)
    {
        chip = (int)(offs >> this->chip_shift);
        chipsel = chip;
    }
    else
    {
        chip = 0;
        chipsel = -1;
    }

    td->version[chip]++;
    if (md)
        md->version[chip]++;

    /* Write the bad block table to the device? */
    if (td->options & NAND_BBT_WRITE)
    {
        res = write_bbt(mtd, buf, td, md, chipsel);
        if (res < 0)
            goto out;
    }
    /* Write the mirror bad block table to the device? */
    if (md && (md->options & NAND_BBT_WRITE))
    {
        res = write_bbt(mtd, buf, md, td, chipsel);
    }

out:
    rt_free(buf);
    return res;
}

/*
 * Define some generic bad / good block scan pattern which are used
 * while scanning a device for factory marked good / bad blocks.
 */
static uint8_t scan_ff_pattern[] = { 0xff, 0xff };

/* Generic flash bbt descriptors */
static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };

static struct nand_bbt_descr bbt_main_descr;

static struct nand_bbt_descr bbt_mirror_descr;

static struct nand_bbt_descr bbt_main_no_oob_descr;

static struct nand_bbt_descr bbt_mirror_no_oob_descr;

#define BADBLOCK_SCAN_MASK (~NAND_BBT_NO_OOB)
/**
 * nand_create_badblock_pattern - [INTERN] Creates a BBT descriptor structure
 * @this: NAND chip to create descriptor for
 *
 * This function allocates and initializes a nand_bbt_descr for BBM detection
 * based on the properties of @this. The new descriptor is stored in
 * this->badblock_pattern. Thus, this->badblock_pattern should be NULL when
 * passed to this function.
 */
static int nand_create_badblock_pattern(struct nand_chip *this)
{
    struct nand_bbt_descr *bd;
    if (this->badblock_pattern)
    {
        pr_warn("Bad block pattern already allocated; not replacing\n");
        return -EINVAL;
    }
    bd = rt_malloc(sizeof(*bd));
    if (!bd)
        return -ENOMEM;
    bd->options = this->bbt_options & BADBLOCK_SCAN_MASK;
    bd->offs = this->badblockpos;
    bd->len = (this->options & NAND_BUSWIDTH_16) ? 2 : 1;
    bd->pattern = scan_ff_pattern;
    bd->options |= NAND_BBT_DYNAMICSTRUCT;
    this->badblock_pattern = bd;
    return 0;
}

/**
 * nand_default_bbt - [NAND Interface] Select a default bad block table for the device
 * @mtd: MTD device structure
 *
 * This function selects the default bad block table support for the device and
 * calls the nand_scan_bbt function.
 */
int nand_default_bbt(struct mtd_info *mtd)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int ret;

    /* bbt_main_descr */
    bbt_main_descr.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP;
    bbt_main_descr.offs = 8;
    bbt_main_descr.len = 4;
    bbt_main_descr.veroffs = 12;
    bbt_main_descr.maxblocks = NAND_BBT_SCAN_MAXBLOCKS;
    bbt_main_descr.pattern = bbt_pattern;

    /* bbt_mirror_descr */
    bbt_mirror_descr.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP;
    bbt_mirror_descr.offs = 8;
    bbt_mirror_descr.len = 4;
    bbt_mirror_descr.veroffs = 12;
    bbt_mirror_descr.maxblocks = NAND_BBT_SCAN_MAXBLOCKS;
    bbt_mirror_descr.pattern = mirror_pattern;

    /* bbt_main_no_bbt_descr */
    bbt_main_no_oob_descr.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP | NAND_BBT_NO_OOB;
    bbt_main_no_oob_descr.len = 4;
    bbt_main_no_oob_descr.veroffs = 4;
    bbt_main_no_oob_descr.maxblocks = NAND_BBT_SCAN_MAXBLOCKS;
    bbt_main_no_oob_descr.pattern = bbt_pattern;

    /* bbt_mirror_no_bbt_descr */
    bbt_mirror_no_oob_descr.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP | NAND_BBT_NO_OOB;
    bbt_mirror_no_oob_descr.len = 4;
    bbt_mirror_no_oob_descr.veroffs = 4;
    bbt_mirror_no_oob_descr.maxblocks = NAND_BBT_SCAN_MAXBLOCKS;
    bbt_mirror_no_oob_descr.pattern = mirror_pattern;

    /* Is a flash based bad block table requested? */
    if (this->bbt_options & NAND_BBT_USE_FLASH)
    {
        /* Use the default pattern descriptors */
        if (!this->bbt_td)
        {
            if (this->bbt_options & NAND_BBT_NO_OOB)
            {
                this->bbt_td = &bbt_main_no_oob_descr;
                this->bbt_md = &bbt_mirror_no_oob_descr;
            }
            else
            {
                this->bbt_td = &bbt_main_descr;
                this->bbt_md = &bbt_mirror_descr;
            }
        }
    }
    else
    {
        this->bbt_td = NULL;
        this->bbt_md = NULL;
    }

    if (!this->badblock_pattern)
    {
        ret = nand_create_badblock_pattern(this);
        if (ret)
            return ret;
    }

    return nand_scan_bbt(mtd, this->badblock_pattern);
}

/**
 * nand_isreserved_bbt - [NAND Interface] Check if a block is reserved
 * @mtd: MTD device structure
 * @offs: offset in the device
 */
int nand_isreserved_bbt(struct mtd_info *mtd, loff_t offs)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int block;

    block = (int)(offs >> this->bbt_erase_shift);
    return bbt_get_entry(this, block) == BBT_BLOCK_RESERVED;
}

/**
 * nand_isbad_bbt - [NAND Interface] Check if a block is bad
 * @mtd: MTD device structure
 * @offs: offset in the device
 * @allowbbt: allow access to bad block table region
 */
int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int block, res;

    block = (int)(offs >> this->bbt_erase_shift);
    res = bbt_get_entry(this, block);

    pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
             (unsigned int)offs, block, res);

    switch (res)
    {
    case BBT_BLOCK_GOOD:
        return 0;
    case BBT_BLOCK_WORN:
        return 1;
    case BBT_BLOCK_RESERVED:
        return allowbbt ? 0 : 1;
    }
    return 1;
}

/**
 * nand_markbad_bbt - [NAND Interface] Mark a block bad in the BBT
 * @mtd: MTD device structure
 * @offs: offset of the bad block
 */
int nand_markbad_bbt(struct mtd_info *mtd, loff_t offs)
{
    struct nand_chip *this = mtd_to_nand(mtd);
    int block, ret = 0;

    block = (int)(offs >> this->bbt_erase_shift);

    /* Mark bad block in memory */
    bbt_mark_entry(this, block, BBT_BLOCK_WORN);

    /* Update flash-based bad block table */
    if (this->bbt_options & NAND_BBT_USE_FLASH)
        ret = nand_update_bbt(mtd, offs);

    return ret;
}
